Chusetts



(NC Model.)

E. C'. C'NEILL. ELECTRIC RESISTANCE CONDUCTOR.

. Patented Feb. 22, 1898.

/ff //f/ WITNESSES ATTH/VEYS.

UNITED STATES PATENT OEEIcE.

IIENRY G ONEILIJ, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR TO THE AMERICAN ELECTRIC HEATING CORPORATION, OF BOSTON, MASSA- onUsE'r'Ts.

4ELECTRIC RESISTANCE-CONDUCTOR.

SPECIFICATION forming part of Letters` Patent No. 599,351, dated February 22, 1898. Application filed January 4, 1897. Serial No. 617,878. (No model.)

I all whom, t may concern:

Be it known that I, HENRY G. ONEILL, a

l Vcitizen of the United States, residing at Brookline, in the county of Norfolk and State of Massachusetts, have invented a new and useul Improvement in Electric Resistance-Condi. etors, of which the following is a specification'.

rlhis invention relates to improvements in electric resistance-conductors for converting electrical energy into heat energy; and its objects are to produce such a conductor at moderate cost, having a high specific resistance, which shall be adapted to withstand very high temperature, such as a red or even a white heat, without oxidation or other permanent change, and to provide an insulatingsupport for the conductor and convenient and durable terminal connections therefor.

Resistance-conductors made in accordance with this invention are designed, primarily, for the generation-of heat-more particularly where very high temperatures are required, as in soldering-irons, branding-irons, and the like, or in the production of light by incandescence. They may be used also as resistances for the purpose of controlling or regulating the current in a circuit, as in rheostats, the generation of heat in this case being merely incidental to that purpose.

To accomplish the objects hereinbefore stated, I use as the conducting material in -my invention one or more of the permanent refractory oxids having eleetroconductive properties, which I combine with other materials of similar non-oxidizable chemical nature, but having a lower conductivity, in such proportions as to obtain a compound of high specific resistance, which I cast preferably in the form of a rod or a filament.

Among the oxids suitable for the purposes of this invention are the protoxid of vanadium, the black oXid of copper, the oxids of chromium, iron, cobalt, nickel, and tungsten, silica, and the complex oxids of silicon with other metals, such as the silicates of aluminium, magnesium, and zirconium.

Among the oXids mentioned the protoxid of vanadium appears to be thel highest in conductivity, while silica and the silicates are lthe device to special requirements.

among the lowest, being, indeed, classed as insulators at low temperature. I have found, however, that with very high temperature the conductivity of these substances is much increased. By mixing the oxids of higher with those of lower electrical conductivity in varying proportions, as by fusing together the protoXid of vanadium or one of the electroconductive iron oxids with a proportion of silica varying between ten and forty per cent., compounds are obtained having a range of resistance suffieientfor most purposes. The practice of the invention, however, is not restricted to the employment of these particular oxids, as a great variety of them may be used, with more or less success, in adapting The insuperable obstacle to the use of many electric resistances, which resides in their liability to oxidation at high temperatures in contact with air, is removed by the use of refractory oxids, which are of course non-oxidizable.

I am aware that certain of the electroconductive o'xids have been employed heretofore in the form of electrodes for electrolytic apparatus, in which case, however, the object has been not to use the conductor as a resistance, but to obtain it in a form having the highest possible conductivity. For the purpose of this invention, however, I combine the oxids in such proportion as to give a high specific resistance, and in order still further to augment their resisting qualities I cast them in the form of rods or filaments or other alternative forms.

In further carrying out the objects specilied it is necessary to provide durable metallic terminal connections firmly attached to each end of the rod or filament of oxid in such a manner that they will not become oxidized or overheated at the points of contact with the resistance material. To accomplish this object, I permanently weld to the ends of the oxid rod metallic wires or terminals, which are preferably of platinum, but maybe in certain cases of copper or other les's refractory metals. This welding in of the terminals I may accomplish by fusing them into the oxid compound by means of an electric are applied to their surfaces of contact; but I prefer to accomplish it in the following manner: The mold in which the resistance-conductor is to be cast is provided with holes through which the ends of the terminal wires are inserted,

so as to project slightly into the mold. The oxid compound having been melted in a crucible is then poured into the mold, so that the ends of the rod or filament are cast around the proj ectin g'ends of the metallic terminals, making thus a very perfect weld.

Further, to fulil the purposes of this invention it is advisable to provide an insulatingsupport for the conductor which shall be able to withstand the temperatures to which it may be heated in service. For this purpose l use a body of refractory material-such as porcelain, re-clay,&c.-Which forms an envelop or support for the conductor. The most perfect support is obtained by forming the mold itself of this refractory supporting-body,insert ing the terminal connections therein, as before described, and casting the resistanceconductor of metallic oxid compound directly therein.

My invention is illustrated in the accompanying drawings, in which- Figure l is a sectional diagram of the chief elements of the invention. Fig. 2, is a sectional diagram of the device in a more complete form, and Fig. 3 is a sectional diagram illustrating one of the principal practical applications of the invention.

' Similar letters indicate corresponding parts in all the views. y

A indicates the rod or filament of resisting oXid compound; B and C, the metallic terminals welded thereto.

l) indicates the insulating support or mold, and E indicates a containin g-body' adapted to be heated by the passage of a current through the resistance-conductor A.

In Fig. 2 the insulating-mold D isshoWn provided with holes f and g, through which may be connected into an electric circuit by means of the terminal Wires -B and C. It may also'be used as la heater without insertion in the enveloping body E. It is also -ob- Vious that if there is any advantage in doing so the cast resistance A may be removed from the mold in which it is cast and used by itself in an electric circuit supported, for

example, by the terminal wires, as indicated in Fig. 1. It may be heated, if desired, by the passage of a sufficient current through it to incandescence and used as a source of light. It is further obvious that in cases Where the resistance-conductor is to be incased in a metallic body which it is desired to heat thereby it is not necessary, though vit may .be advantageous, to retain the cast conductor in its original mold; but it may be taken from the original mold and afterward inserted in a separate envelop of refractory insulating material, as is indicated in Fig. 3.

Here a pair of rods having their terminal Wires C connected together are shown as in serted in a single corel), of refractory material, placed Within a surrounding metallic envelop E, which is adapted to be heated. The terminals B and B are in this case connected to the source of electricity.

As it is apparent that many modifications in detail as to the form of the rods, the nonconducting support, the containing body, rito., may be readily made, while retaining the main elements4 'embodied in my invention, l do not restrict my claims to the special forms of the device shown and described; but

What l claim, and desire to secure by Letl. A resistance-conductor for converting electrical energy into heat energy, consisting of an oxid compound cast in the form of a rod or` iilament,'havin g metallic terminal connections attached to each end thereof.

2. In a device for interposing a resistance in an electric circuit, the combination of an insulating supporting mold with a resistanceconductor of refractory oxid compound castv therein.

3. In adevice for interposing a resistance in an electric circuit, the combination With a cast resistance-conductor of metallic oxid compound, of metallic terminal-conductors Welded thereto.

4. ln a device for interposing resistance in an electric circuit, the combination With an insulating-support of refractory material, of a cast resistance-conductor ofmetallic oXid compound held therein, and metallic terminal conductors Welded to said resistance-conductor.

` ln testimony whereof l have signed my name to this specification in the presence of two subscribing. witnesses.

HENRYG. ONEILL.

' lVitnesses: i

THOMAS J. CUNNINGHAM, ODIN B. ROBERTS. 

